Light emitting diodes (LEDs) have many advantages over traditional lighting sources, such as tubular fluorescent lights, incandescent lights, or high intensity discharge lights. These advantages include high light-electricity conversion rate, small volume, long life, adopting DC current, fixed wavelength low heat generation, and complying with environmental protection requirements. For these reasons, LEDs have become a popular illumination device.
In some applications, it may be desirable to vary the color temperature of the LED lighting, such as varying the light from a cooler temperature (i.e. blue and purple hues) to warmer temperature (i.e. orange and red hues). This may be done by providing two or more banks of LEDs having distinct light frequencies, one that emits warmer light and one that emits cooler light. By dimming one bank of LEDs and brightening the other (or vice versa) the overall light emitted may be faded between warm and cool temperatures.
In systems that employ three or more wires to power and control an LED light this fading may be accomplished with ease by providing a dedicated power wire to the LEDs and providing power intensity signals to dim and brighten the lights. However, when a dedicated power wire is unavailable, such as is the case in certain RV and Marine applications, controlling variation in color temperature is more difficult.
Accordingly, an improved LED light temperature control circuit and method for making and employing the same is needed.